Draft-forming device for furnaces.



J. D. MILNER.

DRAFT FORMING DEVICE FOR FURNACES.

APPLICATION FILED MAY5,1915.

1,167,708.. Patented Jan.11,1916.

npwm Parana oiarieia.

mas era .101111 In. arrinnniayor HUNTINGTON, TEXAS.

DRAFT-FORMING DEVICE FOR FURNACES.

To all whom it may concern Be it known that I, JOHN D. MILNER, a citizen of the United States, residing at Huntington, in the county of Angelina and State of Texas, have invented certain new and useful Improvements in Draft-Forming Devices for Furnaces, of which the following is a specification, reference being had to the accompanying drawings.

My invention relates to draft creating devices for furnaces, and particularly to that type of draft creating device wherein steam is used for causing a current of air to pass through the furnace.

The primary object of my invention is to provide a very simple and effective means of this character which is so located that the air is caused to enter the furnace immediately beneath the grate thereof, and in which this blast of air is caused by steam jets, which, intermingling with the air, pass upward through the burning coal and increase the combustion thereof.

Other objects will appear in the course of the following description.

My invention is illustrated in the accompanying drawings, wherein Figure l is a vertical sectional view of a steam boiler furnace with my improved draft device applied thereto; Fig. 2 is a diametric sectional View of the draft thimble, showing the steam pipe therein; Fig. 3 is an end view of the annular steam pipe on the end of the thimble; Fig. 4 is a fragmentary section on the line 4-1 of Fig. 3.

Referring to these figures, A designates a furnace of any suitable character, but particularly a furnace for burning soft coal or sawdust, and disposed within this furnace is a grate B. The space below the grate is closed bv means of a door C, this door being provided with any suitable means whereby it may be held in air tight engagement with the front of the furnace. All of these parts may be of any suitable construction, as they form no part of my invention.

Mounted within the door C are one or more open-ended thimbles or tubes 2. These of course will vary in size, depending upon the size of the furnace and the size of the door, but under ordinary circumstances these thimbles or tubular members, 2 will Specification of Letters Patent.

Patented Jan. 11, 1916.

Application filed May'5, 1915. Serial No.'26,033.

have a diameter of from 8 to 12", and be about 14 long. Each thimble is flared at opposite ends as at 3, and disposed at the inner end of each thimble slightly inward of the extremitv thereof is an annular pipe i which is perforated at a plurality of points, these perforations 4; being so disposed as to direct the jets of steam which is caused to pass through this pipe in a direction approximatel parallel to the flared wall of the members 2. The pipe 4- is blanked at one end and the other end of the pipe extends longitudinally through the tubular member or thimble to the forward end thereof, and thence out as at 5, this pipe being connected to any suitable source for supplying fluid under pressure thereto. This fluid is preferably steam taken from the boiler. The steam passes through the pipe 5 into the annular portion thereof and is then discharged in a series of jets, the discharge of steam from the orifices in the pipe l causing the indraft of air through the thimble 2 and forcing this air upward through the fuel on the grate B.

It will be noted with regard to this invention that in the first place this draft creating means is disposed below the grate so that the air is forced upward through the fuelon the grate instead of drawn through the fuel by a draft creating means disposed at a relatively great distance from the grate, as in those devices where a steam pipe is located in a stack. Furthermore, it will be noted that with my construction the steam or other agent in the pipe is itself forced or projected into the space immediately beneath the grate, and is there mixed with the indrawn air and carried upward through the fuel on the grate, thus adding materially to the combustion of the coal and developing a greater degree of heat. Furthermore, I find in the practical use of my invention that 1t will not cause sparks to be forced or drawn upward through the stack apd expelled therethrough, as is the case where blowers are used, or where draft creating devices are located in the stack itself. I have further found by a comparison of my device with furnaces in which blowers are used connected with the space below the grate, that a much better combustion of the fuel is secured by my device, and that it is particularly adapted for use in burning soft coal or sawdust.

Having described my invention What I claim is:

An air injector for furnaces, comprising a hollow tubular body flared at opposite ends, an annular pipe disposed in the inner end of the tubular body and having perfo- 10 rations discharging approximately parallel Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

